Many examples of compositions useful as catalysts involved in oxygenated hydrocarbon manufacture and processing are known. Some catalysts are especially useful in production of C.sub.1-10 oxygenated hydrocarbons from synthesis gas (i.e., syngas), which comprises a gaseous mixture of carbon monoxide and hydrogen. Some are most especially useful in processes for production of C.sub.1-5 oxygenated mixed alcohols. Much of the art relating to these processes is concerned with the production of catalysts which enhance productivity when used therein. Especially in processes which convert synthesis gas into C.sub.1-10 oxygenates and most especially in mixed alcohols processes, enhancement of productivity generally relates to improving conversion, the amount of carbon monoxide converted into product, or improving selectivity, the amount of carbon monoxide converted to a given desired product divided by the amount of total carbon converted excluding carbon dioxide by-product. Such a composition which enhances productivity, especially in converting synthesis gas into oxygenated hydrocarbons and in a mixed alcohols process in particular, has a greater catalytic activity in the process in which it is used. The elements and method used to produce such compositions can affect its utility and activity.
For example, Stewart, U.S. Pat. No. 2,490,488 (1949) (incorporated herein by reference), discloses a catalyst made from molybdenum disulfide promoted with an alkali or alkaline earth metal compound, but not alumina or thoria, useful in a Fischer-Tropsch process and discloses that when the catalyst is not so promoted it is useful in a methanation process. The example shows a 30 percent selectivity to C.sub.3 + (i.e., of three carbon atoms and higher) hydrocarbons and oxygenates. Of this 30 percent, at most 14 percent boils near or above 65.degree. C., the boiling point of methanol. Thus, alcohol selectivity is at a maximum of 13.2 percent.
Kinkade (Union Carbide), European Patent Application No. 84116467.6 (published July 24, 1985, Publ. No. 149,255) (incorporated herein by reference), discloses that C.sub.1-5 n-alcohols are substantially produced with a catalyst consisting essentially of molybdenum sulfide and an alkali metal compound. The gas hourly space velocity (i.e., GHSV) must be about 3000 hour.sup.-1 or above. Variations in the GHSV, temperature, pressure and alkali metal compound are disclosed to affect the alcohols' selectivity.
Pedersen et al., British Patent Publication No. 2,065,291 (incorporated herein by reference), disclose a process for making C.sub.2 hydrocarbons from syngas using a catalyst comprising a group VB or VIB metal in combination with an iron group metal, as free metals, oxides or sulfides on a porous oxidic support. The authors note that the presence of hydrogen sulfide alters the activity and selectivity of their process.
Happel et al., U.S. Pat. No. 4,151,191 (1979) and U.S. Pat. No. 4,260,553 (1981) (both incorporated herein by reference), disclose methanation processes with certain unreduced, unpromoted molybdenum and lanthanide- or actinide-containing catalysts.
Hargis, U.S. Pat. No. 4,261,864 (1981) (incorporated herein by reference), teaches a process for making .alpha.-olefins from syngas over an iron tungstate/alkali metal hydroxide catalyst.
Chang et al., U.S. Pat. No. 4,177,202 (1979) (incorporated herein by reference), teach a process for making methane- or ethane-rich hydrocarbons from syngas over a molybdenum catalyst, optionally promoted with cobalt or vanadium. Selectivity to ethane is enhanced by the presence of hydrogen sulfide in the syngas feed.
Murchison et al., U.S. Pat. No. 4,151,190 (1979); U.S. Pat. No. 4,199,522 (1980); and U.S. Pat. No. 4,380,589 (1983) (all incorporated herein by reference), disclose Fischer-Tropsch processes for the production of C.sub.2-4 hydrocarbons and C.sub.2-4 olefinic hydrocarbons with certain Fischer-Tropsch catalysts which contain Mo, W and or Re and an alkali, alkaline earth and/or thorium promoter. Commercially significant quantities of oxygenates such as alcohols from these catalyzed processes are not taught Hydrogen sulfide is taught to affect the catalyst activity.
Anderson et al., Industrial and Engineering Chemistry, Vol. 44, No. 10, pp. 2418-2424 (incorporated herein by reference), disclose a number of catalysts containing zinc, copper, chromium, manganese, thorium, iron, occasionally promoted with alkali or other materials for making various alcohols. The authors state that ethyl alcohol is a major constituent, the yield of methanol is usually very small and a tentative summary of factors favoring the production of alcohols is high pressure, low temperature, high space velocity, high recycle ratio and carbon monoxide-rich synthesis gas.
Naumann et al., U.S. Pat. No. 4,243,553 (1981) and U.S. Pat. No. 4,243,554 (1981) (both incorporated herein by reference), teach certain thermally decomposed hydrocarbylammonium thiomolybdate and oxythiomolybdate catalysts. The catalyst is especially useful for the water gas shift and methanation reactions.
Quarderer et al. (Dow Chemical), European patent application No. 84102932 5 (published Sept. 26, 1984, Publ. No. 119,609) (incorporated herein by reference), discloses that alcohols which boil in the range of motor gasoline are made at good selectivities from syngas with an optionally supported Mo/W/Re and alkali/alkaline earth element catalyst. In certain preferred embodiments, it is disclosed that Mo/W/Re sulfides and carbon supports, when the catalyst is supported, are each favored, and it is preferred to exclude lanthanide and actinide series metal components.
To make a commercially significant C.sub.1-10 oxygenated hydrocarbon or alcohols process, one must use a catalyst and conditions which are highly efficient To be efficient, the catalyst must yield a high weight ratio of product per unit weight of catalyst in a given period of time. The catalyst must be stable and active for long periods of time between regenerations. This may be particularly difficult to accomplish, especially for alcohols, when the H.sub.2 /CO ratio of the feed gas is low, such as less than 2 to 1. Id eally the catalyst will be sulfur tolerant and will have a high selectivity to a commercial product to avoid purification, removal of by-products or separation into two or more product streams.
When the mixed alcohols product is to be used as a fuel replacement or a fuel additive, it may be desirable that the ratio of C.sub.1 to C.sub.2 + alcohols be no greater than a certain amount. Excessive methanol is generally considered an unattractive additive to gasolines. Methanol may decrease drivability and may increase corrosion in the fuel system and may cause phase separation when used in excessive quantities. These problems may be alleviated by blending methanol with higher alcohols.
Accordingly, one may wish to synthesize mixed alcohols with no more than a certain amount of methanol in the blend. Or in a similar fashion, one may wish to minimize the ratio of C.sub.1 to C.sub.2 + alcohols in mixed alcohols so that methanol may be purchased and blended into the mixed alcohols to give the maximum acceptable C.sub.1 to C.sub.2 + alcohols ratio.
A problem in the art is enhancing the efficiency of the overall processes. This includes increasing conversion and selectivity to desired oxygenated hydrocarbon products. And so, improvements in production of C.sub.1-10 oxygenated hydrocarbons are always needed and welcome. They are especially needed and welcome when they are the result of a composition with enhanced and improved catalytic activity and selectivity being used therein.